Welsh shipwreck padlock from 1583 opened after scanners reveal its four-letter code

A brass lock from a 1583 wreck

A 400-year-old brass padlock has been opened after experts identified the four-letter code that secures it. Metal detectorist Peter Hughes found the lock in 1999 in the sand near Margam, in Port Talbot, Wales. It is linked to the Ann Francis, a ship caught in a storm on 28 December 1583 while sailing back from Spain. The lock lay beside Spanish silver coins and two coin weights, and researchers think it may have guarded those objects or a chest holding valuables such as documents or textiles, none of which survived.

Two decades of attempts

Hughes, who is 69 and lives in Maesteg, said he came across the find by chance on a day off, while walking the beach with his metal detector and spotting a coin. The padlock was one of hundreds of artefacts he recovered during decades of searching Morfa beach. He then spent about 20 years trying to open it himself by turning the dials and testing combinations. Hughes said he was delighted that the expert team from Amgueddfa Cymru and Cardiff University had cracked the code after he had struggled with it for so long.

“That was the start of a journey that lasted 21 years.”

“I tried to unlock it for about 20 years, I tried moving the dials, finding the right combinations, and I failed.”

How the code was cracked

Dr David Williams, a research associate at Cardiff University's School of Engineering, said he was sceptical when asked to use a scanning device to solve the puzzle. The team turned to micro-CT scanning to view the lock's internal mechanism without taking it apart. Williams said the equipment was not designed for this purpose, and that the scanner normally handles much smaller items.

“This is micro CT scanning, something you'd get at the hospital, but for smaller items.”

The first scan revealed some letters, while the second produced nothing useful. The third scan, which used a different approach, identified the four letters ANCE. The mechanism has four rings of six letters each, which allows 1,296 possible combinations, and the letters also had to line up with the top of the lock before it would open. Williams said he was amazed the team had actually cracked it.

The wider hoard

The lock is part of a larger collection of objects from the Ann Francis, which was caught in the storm on its way back from Spain. Its cargo stayed buried under the sand for centuries before Hughes began recovering items. Hughes passed the hoard of artefacts to Amgueddfa Cymru in 2017. Experts from the museum and from Cardiff University worked together on the lock, combining their knowledge of the object with the scanning expertise needed to read its hidden mechanism.